When the Muslims first came to Medina, they used to gather and estimate the time of prayer, since no call was made for it. One day they discussed the matter.Some of them suggested, "Take up a bell like the bell of the Christians."Others said, "Rather, a horn like the horn of the Jews."Then Umar said, "Why not send a man to call out for the prayer?"So the Messenger of Allah ﷺ said, "Bilal, get up and call for the prayer."
كان المسلمون حين قدموا المدينة يجتمعون فيتحينون الصلاة ليس ينادى لها، فتكلموا يوما في ذلك، فقال بعضهم: اتخذوا ناقوسا مثل ناقوس النصارى، وقال بعضهم: بل بوقا مثل قرن اليهود فقال عمر: أولا تبعثون رجلا ينادي بالصلاة؟ فقال رسول الله ﷺ: يا بلال قم فناد بالصلاة.
Bukhari narrated it in the Book of Adhan (604), and this is his wording, and Muslim narrated it in the Book of Prayer (377), both through the route of Abdul-Razzaq, and it is found in his Musannaf (1/456). He said, Ibn Jurayj informed us, he said, Nafi informed me, that Abdullah bin Umar used to say, then he related the hadith. Muslim did not mention "a horn" but rather said, "a horn like the horn of the Jews."As for his statement, "Get up, Bilal, and call out for prayer," that means calling out "the prayer, the prayer," and it is not the familiar adhan that Abdullah bin Zayd saw.